A Case Study on Hemp Plastic
Hemp plastic is often touted as biodegradable, but a deeper dive tells the whole story.
One of the greatest myths surrounding hemp is that hemp plastic is biodegradable. This is not entirely false, but it is not entirely true, either. To understand why, we examine some of the materials and terminology surrounding hemp plastic.
biomaterials.
The term “biomaterial” has a wide range of meanings. Merriam-Webster defines the term as “a natural or synthetic material (such as a metal or polymer) that is suitable for introduction into living tissue especially as part of a medical device (such as an artificial joint).” However, this is not what we mean when we are referring to biomaterials.
Instead, we are referring to bio-based materials, which the EPA defines as “products that mainly consist of a substance (or substances) derived from living matter (biomass) and either occur naturally or are synthesized.” This is the category of materials that products made out of hemp belongs to.
bioplastics.
The term “bioplastic” also has a wide range of meanings, understandings, and associated confusion. Merriam-Webster defines it as “biodegradable plastic that is made or derived from biological materials.” However, this does not give us the whole picture.
The fact is that not all bio-based plastics are biodegradable. A slightly more nuanced definition is given by Britannica which clarifies that only “some bioplastics are biodegradable.” Still, there is another layer of complexity to add to this.
Just because something is biodegradable does not mean it is eco-friendly. There are many factors to consider such as whether or not the product is necessary in the first place, how it is used, where it ends up once it is disposed of, and what it biodegrades in to.
For the sake of this case study, we will limit our focus to whether or not hemp plastic is truly biodegradable as is so often claimed. As always, there will be much room for discussion and many paths to take going into the future.
hemp plastic.
One of the biggest manufacturers in the space, The Hemp Plastic Company (THPC), lists five different polymers on their website:
Hemp polylactic acid (PLA)
Hemp bio-based high density polyethylene (HDPE)
Hemp high density polyethylene (HDPE)
Hemp polypropylene (PP)
Hemp acrylonitrile butadiene styrene (ABS)
Let’s focus on the first option, since that is the only bio-based and compostable option out of the five.
PLA
PLA stands for polylactic acid and is often marketed as biodegradable, eco-friendly, and environmentally sustainable. It is usually made of starch from corn or sugar cane.
However, in a backyard experiment, PLA did not degrade after two years in dirt, water, or the elements of nature.
That is because PLA is industrially compostable, not home compostable. This means it requires a specific set of circumstances to break down which can only be found in industrial composting facilities (and a select few, at that).
This highlights the distinction between materials that are “bio-based,” “biodegradable,” and “compostable.”
In summary, PLA is bio-based, but not biodegradable, at least not in the same way the leaves of a hemp plant would be.
“Hemp Plastic"
All of the hemp plastics on THPC’s website contain only 25% hemp. What exactly does this entail?
The website does not say specifically, but, again, an educated guess can be made. Another company called HEMPZOO has a PLA-based hemp plastic filament listed for sale which is described as being made of “biodegradable thermoplastic and short hemp fiber.”
Again, the word “biodegradable” here is misleading (even if unintentionally), as PLA is not bio-degradable in the traditional sense. However, the “short hemp fiber” from which the rest of the filament is made may, in fact, be biodegradable, provided that the fiber has not been processed in such a way as to alter its biodegradability.
The fiber of the hemp plant can be obtained in various ways. It comes from the stalk of the plant, which is composed of the outer bast and the inner hurd. The outer bast is used to make long fiber while the inner hurd is used to make short fiber (source).
The inner hurd is the “woody” part of the stalk which contains the most cellulose. This cellulose can be used to make rayon, celluloid, cellophane, and other cellulose-based materials.
Neither THPC or HEMPZOO provide any links or evidence to back up their claims that their products are biodegradable or compostable. While the claim can be made that, in theory, these products can be industrially composted, it is often the case that this does not end up happening and that the products end up in a landfill or worse. This is not to say that we should not produce hemp plastic or pursue alternative means of plastic production, but it begs the question: who is ultimately responsible for where these products end up?
final thoughts.
Given the obscurity and misinformation surrounding hemp plastic and bio-based plastics in general, it cannot be stated that hemp plastic is, in fact, a better alternative than any other bio-based plastic on the market today. This may change with time as more research is done.
Instead of focusing on bio-based single-use materials as a solution for sustainability, the conversation must shift towards truly sustainable alternatives such as reusable items and creating proper infrastructure for products to be recycled and composted in the first place.
Are there any companies who are making pure hemp-based, biodegradable plastic? Not that we are aware of. This is why we choose to set our focus on materials and ways of doing things that are truly biodegradable. In the case of hemp, this means keeping all the natural goodness of the plant intact and not mixing it with harmful materials.
One company, Pollima, is doing just that by taking hemp byproduct and pressing it into furniture. The results are beautiful, iconic pieces of furniture that are not only biodegradable at end-of-life but also reusable for years and years. What better way to celebrate such an amazing plant than by allowing it to live up to its fullest potential?